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Fig. Percentage share of different food items in the foregut of Colymbetes fuscus and C. striatus (animal contents). A – C. striatus in the Zehlau Peatbog, B – C. fuscus in the Zehlau Peatbog, C – C. striatus in the Biebrza Marshes, D – C. fuscus in the Biebrza Marshes.
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The study involved the analysis of the foregut content of 120 adult specimens of Colymbetes fuscus and C. striatus collected in aquatic habitats in the Biebrza Marshes (Poland) and the Zehlau Peatbog (Russia). The gut content comprised animals (including eggs of aquatic invertebrates), plants and detritus. Larvae of Ephemeroptera were common in bee...
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به منظور شناسایی ، تراکم و پراکنش زئوپلانکتون ها و تغییراتشان طی 3 مرحله نمونه برداری از زمستان 1388 الی تابستان 1389 انجام پذیرفت. نمونه ها توسط تور پلانکتون گیر کمرشکن 55 میکرون (Juddy Net) انجام شد. نمونه ها توسط فرمالین به نسبت 4 درصد تثبیت و در آزمایشگاه با میکروسکوپ معکوس مطالعه شدند. در این بررسی بطورکلی 6 شاخه زئوپلانکتونی در 31 جنس شناسایی...
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... They are a group of organisms that are highly diverse in terms of species and ecology, are widespread in the environment and typically occur in large numbers in very different habitats 15 . The literature shows that beetles use a pool of nutrients from different trophic levels, although most beetles are predatory, which underlines their important role in trophic networks as regulators of the numbers of other organisms 13,14,16,17 . The classification of beetles into specific functional groups, indicating not only the type of food consumed but also the way food is obtained, is extremely important for a more comprehensive analysis of trophic networks 12,18,19 . ...
... Our PCA results (Fig. 6) confirm the observations that species preferring waters with higher mineralisation often have an affinity for peat bog waters and are relatively more numerous among acidophilic tyrphophilous species 58,59 . Water beetles are among the organisms that tap various food resources [14][15][16]59 . Species from the families Dytiscidae, Noteridae and Gyrinidae are actively hunting predators, Hydrophilidae are mainly shredders and feed on macromolecular organic material, although Hydrophilus sp. ...
... Some hydrobiologists 14,16,17,[60][61][62] emphasise in their studies that predatory beetles feed on quite different foods depending on the food supply and body size (of both the predator and its prey). The beetle feeds mainly on other insects, especially Ephemeroptera, Chironomidae, but also on other Diptera, Heteroptera, ground beetles that happen to fall into the water, frog eggs, fish fry, adult beetles and their larvae, even of the same species. ...
The relationships between the species that form the networks in small dystrophic lakes remain poorly
recognised. To investigate and better understand the functioning of beetle communities in different
ecosystems, we created three network models that we subjected to graph network analysis. This
approach displays correlation–based networks of connections (edges) between objects (nodes) by
evaluating the features of the whole network and the attributes of nodes and edges in the context
of their roles, expressed by centrality metrics. We used this method to determine the importance
of specific species in the networks and the interspecific relationships. Our analyses are based on
faunal material collected from 25 dystrophic lakes in three regions of northern Poland. We found a
total of 104 species representing different ecological elements and functional trophic groups. We
have shown that the network of relationships between the biomass of species differs considerably
in the three study regions. The Kashubian Lakeland had the highest cohesion and density, while the
network in the Suwalki Lakeland was the thinnest and most heterogeneous, which might be related
to the fractal structure and the degree of development of the studied lakes. Small–bodied predators
that congregated in different clusters with species with similar ecological preferences dominated all
networks. We found the highest correlations in the Masurian Lakeland, where we obtained the highest
centralisation of the network. Small tyrphophiles typically occupied the central places in the network,
while the periphery of the network consisted of clusters with different habitat preferences, including
large predators. The species that were most important for network cohesion and density were mainly
tyrphophilous species, such as Anacaena lutescens, Hygrotus decoratus, Enochrus melanocephalus and
Hydroporus neglectus. The values of attributes determining the role of species in community networks
were influenced by both biotic and environmental factors.
... They are a group of organisms that are highly diverse in terms of species and ecology, are widespread in the environment and typically occur in large numbers in very different habitats 15 . The literature shows that beetles use a pool of nutrients from different trophic levels, although most beetles are predatory, which underlines their important role in trophic networks as regulators of the numbers of other organisms 13,14,16,17 . The classification of beetles into specific functional groups, indicating not only the type of food consumed but also the way food is obtained, is extremely important for a more comprehensive analysis of trophic networks 12,18,19 . ...
... Our PCA results (Fig. 6) confirm the observations that species preferring waters with higher mineralisation often have an affinity for peat bog waters and are relatively more numerous among acidophilic tyrphophilous species 58,59 . Water beetles are among the organisms that tap various food resources [14][15][16]59 . Species from the families Dytiscidae, Noteridae and Gyrinidae are actively hunting predators, Hydrophilidae are mainly shredders and feed on macromolecular organic material, although Hydrophilus sp. ...
... Some hydrobiologists 14,16,17,[60][61][62] emphasise in their studies that predatory beetles feed on quite different foods depending on the food supply and body size (of both the predator and its prey). The beetle feeds mainly on other insects, especially Ephemeroptera, Chironomidae, but also on other Diptera, Heteroptera, ground beetles that happen to fall into the water, frog eggs, fish fry, adult beetles and their larvae, even of the same species. ...
The relationships between the species that form the networks in small dystrophic lakes remain poorly recognised. To investigate and better understand the functioning of beetle communities in different ecosystems, we created three network models that we subjected to graph network analysis. This approach displays correlation-based networks of connections (edges) between objects (nodes) by evaluating the features of the whole network and the attributes of nodes and edges in the context of their roles, expressed by centrality metrics. We used this method to determine the importance of specific species in the networks and the interspecific relationships. Our analyses are based on faunal material collected from 25 dystrophic lakes in three regions of northern Poland. We found a total of 104 species representing different ecological elements and functional trophic groups. We have shown that the network of relationships between the biomass of species differs considerably in the three study regions. The Kashubian Lakeland had the highest cohesion and density, while the network in the Suwalki Lakeland was the thinnest and most heterogeneous, which might be related to the fractal structure and the degree of development of the studied lakes. Small-bodied predators that congregated in different clusters with species with similar ecological preferences dominated all networks. We found the highest correlations in the Masurian Lakeland, where we obtained the highest centralisation of the network. Small tyrphophiles typically occupied the central places in the network, while the periphery of the network consisted of clusters with different habitat preferences, including large predators. The species that were most important for network cohesion and density were mainly tyrphophilous species, such as Anacaena lutescens, Hygrotus decoratus, Enochrus melanocephalus and Hydroporus neglectus. The values of attributes determining the role of species in community networks were influenced by both biotic and environmental factors. The extensive literature on hydrobiology is dominated by publications in which much attention is paid to the structure of biocenoses and the relationships between organism communities and specific environmental conditions 1-11. In contrast, organism communities are relatively rarely studied from a functional perspective, as an intricate network of interactions in a broadly defined predator-prey system in which biomass flows 12,13. The structure and functioning of networks between different species in freshwater has hardly been studied yet 13. It is clear that invertebrates, including beetles, are the dominant component of trophic networks of aquatic ecosystems 13,14. They are a group of organisms that are highly diverse in terms of species and ecology, are widespread in the environment and typically occur in large numbers in very different habitats 15. The literature shows that beetles use a pool of nutrients from different trophic levels, although most beetles are predatory, which underlines their important role in trophic networks as regulators of the numbers of other organisms 13,14,16,17. The classification of beetles into specific functional groups, indicating not only the type of food consumed but also the way food is obtained, is extremely important for a more comprehensive analysis of trophic networks 12,18,19. The application of graph theory-based network analysis is becoming increasingly popular as a research tool in aquatic ecosystem ecology, as it provides greater insight into biocoenosis structure, formation, trophic functioning and responses to changing environmental conditions, especially when modelling is based on data collected OPEN
... Most of the dytiscid species recorded in this study prefer shallower habitats with dense vegetation (Nilsson and Holmen 1995;Nilsson and Söderberg 1996). Vegetation provides them with cover from predators, sites for oviposition, and food sources for some species (Yee 2010; Gioria et al. 2010;Frelik 2014a). The occurrence of vegetation, however, is minimal in deep water compared to shallow areas of a water body, due to poor light penetration (Weisner 1991). ...
Blue infrastructure is an important component of urban green infrastructure, due to its capacity for water cycle regulation and soil formation, as well as supporting unique biodiversity. Urban ponds, as part of urban blue, can harbour a diverse assemblage of aquatic macroinvertebrates. As yet, it is not clear how urbanisation affects macroinvertebrate diversity. In this study, we focus on diving beetles (Dytiscidae) in the Helsinki Metropolitan Area, Finland, to investigate how urbanisation affects their diversity, as well as the effects of margin steepness and the presence or absence of fish on urban dytiscids. We sampled dytiscids using 1-L activity traps in 14 fishless ponds and 11 ponds with fish, at ten sites. We applied generalised linear mixed models (GLMM) and non-metric multidimensional scaling (NMDS) to analyse the effects on dytiscid assemblages. We found that urbanisation had a negative effect on species richness but not on abundance. Steepness of pond margins and the presence or absence of predatory fish, affected both species richness and abundance: dytiscids prefer ponds with gently sloping margins; they have 80% higher species richness and are 79% more abundant in fishless ponds, and medium to large-sized dytiscid species are more capable of coexisting with fish. Urban wetlands can support a diversity of dytiscids at the regional level, and the presence of ponds without predatory fish is beneficial for maintaining dytiscid diversity. We recommend maintaining a diverse range of ponds and wetland habitats for the maintenance of aquatic biodiversity in urban regions.
... They are important factors in eliminating detritus, water filtration, consuming vegetation and minor invertebrates. At the same time these insects are the food basis of fish and invertebrates, to name only a few: certain species of leeches (Kutschera 2003), dragonfly larvae (Elliot 2004) and adult aquatic beetles (Gautam & Goutam 2006;Klecka & Bukal 2012;Frelik 2014a). ...
... For the herbivorous larvae of mayflies, fry seeking shelter from larger predators and the larvae of certain types of midges, aquatic vegetation growing in the littoral zone of water bodies constitutes a primary habitat. Intensive studies on the predation of adult water beetles of the Dytiscidae family have revealed that medium-sized predators were likely to prey also on Ephemeroptera larvae (Frelik 2014a), while the largest predators would additionally consume fry (Frelik 2014b). Furthermore, it appeared that the smallest beetles preferred to consume large numbers of plankton. ...
Predation is an exceptionally important interaction observed in the natural environment. It regulates the population size of potential prey and at the same time decreases competitiveness between them. Among predators inhabiting water environments, especially notable predators are water beetles, particularly adults of Dytiscidae. The results presented herein are an attempt to learn the trophic relations between adult Dytiscidae and non-biting midges (Diptera: Chironomidae). The studies were conducted in one-month intervals from April to September 2012–2013. In the diet structure of adult Dytiscidae of two size categories, the genus Glyptotendipes was found to be prevalent. The largest beetles tended to choose Chironomidae larvae significantly larger than those selected by medium-sized beetles. The diet was mainly composed of Chironomidae larvae related to aquatic vegetation, while larvae inherently connected with detritus were fewer. Statistically significant correlations were confirmed between the population size of Chironomidae larvae and adult insects consumed by beetles of medium body size. No such correlation was found in case of the largest beetles. The study revealed that despite the unquestionable influence of body size and the predation environment on the dietary selectivity of predatory Dytiscidae, the structure of consumed food is subject to noticeable seasonal variations, occurring from spring to autumn.
... Results of studies based on the analysis of digestive tract content are also available. Unfortunately, studies based on analysis of proventriculi content were conducted on small-and medium-sized insects (Dettner et al. 1986, Deding 1988, Hicks 1994, Bosi 2001, Kehl&Dettner 2003, Frelik 2014). The objective of this study is to determine the prevalence of fish fry in the diet of imagines of large Dytiscidae in relation to other elements of the diet, based on the contents of digestive tracts of insects living in the natural environment. ...
The presented study describes the presence of fish fry in the diet of imagines of large Dytiscidae. The study was conducted between March and September in 2012 and 2013. A total of 163 large, aquatic, diving beetles were caught, which represented the following species: Dytiscus marginalis, Dytiscus circumcinctus, Cybister lateralimarginalis. Fish were identified by scales, bones, vertebrae, pharyngeal teeth. Insects were identified by epicrania, mandibles, hooks, limbs, body segments, eyes and wings. Crustaceans were identified by limbs and Oligochaeta by bristles. Seeds and eggs of invertebrates were found whole and intact. Fragments of fish fry were found in the digestive tracts of all three species collected in three studied ponds. The alimentary canals of the studied beetles contained also fragments of insects, detritus, plant tissue, Crustacea, Arachnida, other invertebrates, Oligochaeta, and Gastropoda.
Predaceous diving beetles (Dytiscidae) are a highly speciose group of insects occurring in a large variety of habitat types, where they often form multispecies assemblages, due to their high diversity and large variation in the degree of habitat specificity. While most species have broad habitat preferences, some are specialized for life under extreme habitat conditions. In this chapter, we provide an overview of the main habitats in which dytiscids occur and summarize some of the habitat variables that contribute most to shaping the distribution of dytiscids across habitats and landscapes. These include a range of abiotic conditions and plant–beetle relationships, which act as major habitat selection factors. We discuss how a variety of habitats in agricultural and urban landscapes can contribute to maintain high dytiscid diversity. We then describe some of the most peculiar habitats where dytiscids occur, including phytotelmata, subterranean and interstitial habitats, rock pools, and terrestrial habitats. Over the past couple of decades, examination of habitats that had been typically underexplored for dytiscids has led to the discovery of new species and even new genera. These studies suggest that further exploration of these habitats and the increasing availability of phylogenetic data will provide important insights into the ecology and evolutionary history of species colonizing extreme habitats. This is in turn critical to improve our understanding of the vulnerability of dytiscids to global environmental changes associated with changes in habitat characteristics and availability.
This paper investigates the relations between the diet structure of predaceous adult water beetles from the Dytiscidae family and the structure of macrofauna inhabiting the same environments.
The field studies were carried out from April until September in 2012 and 2013 in one-month intervals. In total, more than 1.000 water beetles and 5.115 benthic macro-invertebrates were collected during the whole period of the study. Subsequently, 784 specimens of adult water beetles (70.6% out of the total sampled) with benthic macro-invertebrates found in their proventriculi, were subject to analysis. The predators were divided into three categories depending on their body size: small beetles (from 2.3 to 5.0 mm), medium-sized beetles (13-15 mm) and large beetles (27-37 mm).
All adult Dytiscidae consumed primarily Ephemeroptera and Chironomidae larvae. Although Asellidae were numerically dominant inhabitants of the sites, the adult water beetles did not feed on them.
The analysis of feeding relations between predators and their prey revealed that abundance of Ephemeroptera, Chironomidae, and larval Dytiscidae between the environment and the diet of adult Dytiscidae were strongly correlated
